Electro-hydraulic actuator digital twin development for hydraulics components prognostics

Modern aircraft are often designed following the More Electric philosophy, but in some cases, like in the primary flight control, the EHAs (Electro-Hydraulic Actuators) are still widely used. In the first part of the thesis, the different actuation systems are presented with their various features, followed by an analysis of the servo-valve types most commonly used in electro-hydraulic actuation systems. This first part concludes with analyzing different servo valve characteristics such as non-linearities, focusing on the friction phenomenon and the most critical models. Among the friction models, theoretical and numerical models are analyzed. The modeling of friction in a numerical environment is undoubtedly the most complex. The computational reference Simulink model is presented in the second part of the thesis. The various elements of the model are analyzed in detail to understand its potential. After the analysis of the reference model, the Simscape model is presented. The Simulink and Simscape environments are different because the latter allows the modeling of physical elements. These differences generate discrepancies that are subject to analysis in this thesis. The various elements of the Simscape model have been characterized thanks to an iterative test campaign to present the same behavior as the reference element. In some of the most critical parts of the system, different solutions are proposed and compared to obtain the best achievable model, which comes closeto the reference model. For the validation of the proposed model, this is tested with different inputs with different curves and amplitudes. The simulations confirmed the correct modeling of the Electro-Hydraulic servomechanism in Simscape, allowing the subsequent development of diagnostic and prognostic algorithms.